Rough agalinis (Agalinis aspera) COSEWIC assessment and status report: chapter 3

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Species Information

Name and classification

Agalinis Raf. is a New World genus with about 60 species in North and South America. Pennell (1929) originally recognized 38 species from North America but later reduced that to 35 (Pennell 1935). Current studies (Canne-Hilliker and Kampney 1991) accept 32 North American species. Pennell (1929) divided the genus Agalinis into six sections with Agalinis aspera alone in the Section Asperae based on vegetative anatomy. Like those species in the section Heterophyllae, A. aspera has an elongated seed capsule but unlike them it also has sepals united to form calyx lobes which are only half the length of the tube. Pennell also considered the narrow elongated leaves to be distinctive. Canne-Hilliker and Kampney (1991) also divide the genus into six sections but with several changes including moving A. aspera into Section Purpurea Subsection Pedunculares. Thus under this reclassification of the sectional and sub-sectional ranks A. aspera is no longer in its own unique section. Agalinis is a taxonomically complex genus that has generated much study of the phylogenetic relationships among the different sections.

This species was first described as Gerardia aspera by Douglas, who collected the type specimens in 1827 in the present province of Manitoba (Pennell 1929). It was first recorded as Agalinis aspera (Dougl.) Britt. in Britton and Brown’s “Illustrated Flora of the Northern United States and Canada ed. II” (1913). The previous Agalinis greenei Lunell is included in A. aspera (Pennell 1929). The Manitoba plants seem to fit the type described as A. greenei (the type specimen of which was collected at Leeds, ND, 80 km south of the MB border) because they are short and have few branches. This type may be a form of genetic diversity adapting the species to the periphery of its range.

Agalinis was considered part of the family Scrophulariaceae until recent work determined that all parasitic Scrophulariaceae should be separated into the family Orobanchaceae (Olmstead et al., 2001).

This species does not have a widely accepted common name; it is also known as: rough purple agalinis (Britton and Brown 1970), rough gerardia (NPWRC 2005), and rough false foxglove (USDA, NRCS 2004 The Plant Database).

In Manitoba, two other taxa have been described in addition to A. aspera. Agalinis tenuifolia Vahl var. parviflora Nutt., which has been found in several southern Manitoba locations: Giroux, Pinawa, Marchand, Vita, Tolstoi, Gardenton. It is characteristically east of the Red River, while Agalinis aspera is found west of the Red River. Scoggan (1957) also lists A. paupercula (Gray) Britton. Budd’s Flora (Looman and Best 1979) records Agalinis purpurea (L.) Pennell var. parviflora (Benth.) Boiv. from “moist grassland in southeastern Parklands”. The Manitoba Conservation Data Centre lists three species: A. aspera, A. tenuifolia var. parviflora and A. paupercula var. borealis, which is considered synonymous with A. purpurea var. parviflora. The Herbarium at the University of Manitoba, Winnipeg (WIN) also has records of only two species (A. aspera and A. tenuifolia). Obviously, great care must be taken in identification of A. aspera in the field to ensure that the correct species is being studied. Budd’s A. purpurea and Scoggan’s A. paupercula can be distinguished by the pedicels that are shorter than the calyx or capsule. Agalinis tenuifolia has very slender pedicels that are generally longer than those of A. aspera. The capsules of A. tenuifolia are globose compared with A. aspera’s ellipsoid to ellipsoid-ovoid capsules, and the corolla of the flower is much smaller. Agalinis aspera is always rough to touch owing to its scabrous or hispidulous-scabrous leaves.

Other species of Agalinis are considered rare, including the following: Agalinis acuta is federally listed as endangered in the USA; Agalinis gattingeri is listed as endangered in Canada.

Morphological description

This description is based on Pennell (1929), Pennell (1935), Britton and Brown (1970) and personal observations on fresh and herbarium specimens from Manitoba.

Agalinis aspera is an annual hemiparasitic herb with a slender erect stem. In its more southern range in the United States this species is known to be 20 – 80 cm in height but Manitoba specimens are only 8 – 35 cm (Table 1). Plants may have many ascending branches in the southern range, but in Manitoba stems are simple or with one or two small branches. The narrow linear leaves are opposite to sub-opposite 1 – 4 cm long, 0.8 – 1.5 mm wide. They are scabrous on the upper surfaces. (This gives the plant its rough feel, hence the common name). The elongate racemes are 4 –18 flowered. The slender, nearly erect flower-bearing pedicels are 4 – 13 mm long, equal to or two times as long as the calyx, while capsule-bearing pedicels lengthen slightly to 5 – 20 mm. The puberulent calyx is made up of five united sepals with acute calyx teeth one-third as long as the 4 – 7 mm tube. The corolla of five united petals is 15 – 25 mm long. The lobed campanulate tube is purple-pink in colour, evanescent, falling the first day (Figure 1). The dark brown seed capsules are oval and oblong, extending well beyond the calyx. They are 7 – 11 mm long. The seeds are 1.2 – 1.4 mm long, oval-angulate, somewhat diamond-shaped.

Figure 1. Agalinis aspera in bloom at Grosse Isle, MB, Aug. 16, 2004 (photograph by M. Hughes).

Genetic description

Chromosome numbers have been studied in 19 species of the genus Agalinis, but unfortunately no counts are available for A. aspera. Other species were found to have meiotic counts of n=13 or n=14 and mitotic counts of 2n=26 or 2n=28 (Canne 1984).